1. Field of the Invention
The present disclosure relates to a method and an apparatus for minimizing propellant emissions during the filling of aerosol containers, and more particularly, to purging devices and methods that utilize purge media to minimize propellant emissions.
2. Description of the Background of the Invention
A common method of charging an aerosol container with a propellant is a standard pressure filling process. In this process, the propellant is forced into the container through and around an aerosol valve stem that extends from the container. This is generally accomplished with a filling apparatus that fits over the valve stem and seals the container environment and/or engages the valve stem in a sealed relationship. The valve stem is depressed and the propellant is introduced under pressure into and around the valve stem. After this filling process, the apparatus is retracted and excess propellant left within the apparatus and the valve stem is released into the surrounding air. Release of certain propellants has been identified as a potential ecological problem and has been a factor in the motivation to develop technologies that prevent such release. Conventional solutions to this problem have involved the use of purging gases, such as nitrogen, to purge propellant from voids in the filling apparatus and the valve stem prior to the retraction of the apparatus. However, a significant amount of propellant is still released into the atmosphere following the retraction of the filling apparatus using these conventional solutions. There is a need to minimize propellant emissions during the filling of aerosol containers that has not been met by the current art.
As noted above, the prior art includes numerous examples of pressure filling apparatuses and processes that do not provide a solution to the release of propellants into the atmosphere. For example, one known process for filling a can with a pressurized propellant or a product includes disposing the can beneath a crimper head. The can includes an unsealed closure disposed on a top of the can, wherein the closure includes a dip tube and a spray nozzle. The crimper head is lowered to engage the top of the can to form a seal around a rim of the can. A vacuum is applied to the can to lift the closure from the top of the can and to remove any residual air or vapor from within the can. The propellant or product, in either liquid or gaseous form, is introduced into the can under pressure. After introduction of the propellant or product into the can, the container is lifted upward a small distance and the closure is crimped to the can.
In another known filling apparatus, a container includes a valve assembly disposed on a top opening of the container. The valve assembly includes an inlet port that is connected to an inlet passageway. A supply nozzle is provided that may be connected to the inlet port. Liquid is transferred from a liquid supply and sent progressively through the supply nozzle, inlet port, and inlet passageway into the container. Further, a relief passageway connects the interior of the container to a relief port outside the container.
Yet another known filling apparatus for filling aerosol cans with a pressurized liquid includes a base with a can support assembly wherein the can support assembly comprises a support platform that can be urged upward by a biasing spring. A can is disposed on the support platform during a can filling operation, wherein the can is moved upward to force a filling orifice of the can into a can receiving element. The can receiving element aligns the filling orifice of the can with a discharge orifice of a liquid reservoir to place the can in a filling position. The liquid reservoir has a tapered bottom in fluid communication with a pump rod receiving aperture. A downward motion of a main piston pump rod through the filling reservoir and into the aperture pressurizes the fluid prior to being discharged through the discharge orifice and into the filling orifice of the can. A ball check valve assembly forms a closing mechanism that allows the filling reservoir to be pressurized only by the downward motion of the piston, and not by the upward release of propellant from the can. The can is disengaged from this filling position by depressing a lever mechanically connected to the support platform.
In a different known filling process, a dispenser device includes a receptacle and a dispenser member, such as a metering valve, for dispensing a fluid such as an active substance or propellant. The dispenser member is assembled onto the receptacle in a leak-tight manner and a predetermined amount of propellant is introduced into the receptacle and/or dispenser member. After filling the dispenser device with propellant, the device is stored for a predetermined period of time and then tested for defects, such as a leak. The dispensers that pass the defect test are filled with the active substance.
Yet another known filling apparatus for filling containers with propellant includes an aerosol container filling adapter that is placed in a sealed relationship with a valve cup of the container. The valve cup includes interior walls, a bottom wall and a central island. An aerosol valve is disposed within the island, wherein the aerosol valve includes a valve stem extending therefrom and through the island and outside the container. The valve stem further extends into a bore of the adapter. A metered volume of propellant is delivered through a passage of the adapter and into the bore, wherein the pressure in the bore is sufficient to depress the valve stem. The aerosol valve is therefore opened and propellant is injected through the valve and into the container.